Mechanical fuse for artillery projectiles



1,641,939 Sept. 6, 1927. A. VARAUD MECHANICAL FUSE FOR ARTILLERY PROJECTILES Filed June 0, 1925 Patented Sept. 6, 1927.

UNITED 'A'rer @FHC.

ANDRE VARAUD, OF GENEVA, SWITZERLAND.

The invention relates to mechanical fuses for artillery projectiles of the type in which the release of the striker device is controlled by a rotary member, the angular position of which can be set prior to firing and which during the flight of the projectile is driven by a clockwork movement in a direction opposite that to which it is timed in being set. A similar clockwork mechanism for time fuses is disclosed in my copending application, Serial No. 712,960 filed May 13, 1924 in which the rotary member consists of an annular gear construction.

'It concerns more particularly the mechanism in these fuses which is actuated at the moment of firing with the aid of a timing device for efiecting simultaneously the winding of the power spring of the clockwork and the setting of the angular position of the rotary member, thereby determining the time of ignition of the projectile.

In the known fuses of this type, the driving member (spindle of barrel or rotary barrel) rotates at the same speed as does the rotary member controlling the release. Since this latter member can perform at the maximum but a single complete revolution, it follows that there is but a single winding revolution at the maximum available and a 30 fact which constitutes three grave defects:

Firstly, the mechanical connection directly between the motive member and the rotary setting member has the efiect that the amount of motive power necessary for driving the latter member is relatively considerable.

Moreover, since but one revolution at the maximum for rewinding is available, the storing capacity of the motive force in the 40 power spring is very small and the number of the'diflerent setting positions available is forcibly restricted by the impossibility to subdivide the dial of the timing apparatus in more than a practically restricted numher of subdivisions.

Finally and particularly the fact that the driving member can describe but one revolution at the maximum even for the longest duration of the function renders it necessary to make use of a very great multiplication between this driving member and the last moving member of the gear train of the clockwork employed for regulating the transmission of the motive power, since this 5" gear(which usually is an escapement wheel)--1nust rotate at a speed sufliciently ARTILLERY PROJECTILES.

. 38,498, and in Switzerland August 2, 1923.

great to be capable of performing the funct1on of a regulating member. The power available being already considerably re-' duced by that used for driving the rotary setting member, the said considerable multiplication makes it very clifficult,if not impossible-to conserve a suflicient amount of power for overcoming the perturbating effects acting on said last moving member during the trajectory of the projectile, (effects of inertia, nutation, centrifugal force, and the like).

The mechanism for the simultaneous winding and setting of a mechanical fuse which embodies the present invention overcomes all the difficulties hereinbefore enumerated and preferably comprises a rotary setting member, a clockwork driving member, reduction gears in constant mesh with the said members in order to distribute the total duration of the movement of the fuse upon several winding turns, together with means for actuating the driving member in the setting operation and also for releasing the driving member to permit the same to become operative upon the firing of the fuse.

By thus distributing the total duration of the movement of the fuse on several winding turns it becomes possible on the one hand to store a much greater driving force in the power spring and to obtain a very much larger number of different angular setting positions, and on the other hand, to sufliciently reduce the necessary multiplication for actuating the last moving member serving for the regulation with a power which sufiices for overcoming all the disturbing effects which during the trajectory of the projectile become active on this moving member.

The attached drawing shows by way of example an embodiment of the object of the invention.

Figure 1 is an axial section of a complete fuse embodying my present invention.

Figure 2 a cross section along the line A-A of Figure 1.

Figures 3 to 6 are other cross sections along the lines B-B, C-C, DD and EE respectively of Figure 1.

Referring to Figure 1, it will be seen that the body of the fuse is made in two parts 1 and 2; it is hollow internally so as to enable the whole of the parts of the clockwork mechanism and of the detonator mechanism to be accommodated therein, and has its pcriphery provided with the groove and usualscrew threaded portion for its connection to the ogival portion of a double acting shrapnel shell.

Axially mounted inthe ogival part 2 so 'as to be freely rotatable about itself is a key 1 serving for simultaneously winding and setting the fuse. 6 indicates a radial binding screw adapted to prevent axial displacement of the key {l relatively tothe body of the fuse. I

The clockwork mechanism'of the fuse is housed in a casing 28 adapted to be inserted as a whole in a cylindrical cavity provided in the body 1 of the fuse. Arranged in this body, moreover, isa lower cavity 7 of smaller diameter for the accommodationof the detonating device, which latter maybe of any known appropriate type, and for this reason has not been illustrated.

The power spring of the clockwork is accommodated in a drum shaped member 30 forming part of the clockwork casing. Its outer extremity is fixed to the internal wall of this drumand its inner end is secured to a lug 38 mounted onthe square portion of the power shaft 39 of the fuse.

This shaft is located in the axis of the fuse, and is journalled at its two extremities in the casing of the clockwork.

This power shaft 39 carries on the one hand keyed to its upper end, Figure 1, a winding pinion 42 adapted to be rotated by means of the key. 4 in a manner hereinafter described, and on the other hand keyed to its lower extremity a setting pinion 43.

This pinion meshes with a gear wheel 44; keyed on a small auxiliary setting shaft 51 having its two ends freely journalled in the clockwork casing. Formed on the lower end of this shaft 51 is a pinion 5 1 in mesh with a gear wheel 55 which is integral with the rotary setting member 56.

This disc shaped member 56 is freely mounted on a screw support 57 screwed into the clockwork casing; and is lodged in a cavity 58 provided in this casing.

This cavity 58 forms a groove 58 for the operation therein of a nipple 59 carriedby the disc 56.

This nipple co-operates withthe nose 60 of a lever 61 (Figure 6) which is rotatably mounted on a screw 62 in a recess 63 in the clockwork casing, and is subjected to the action of a spring 64 tending to move the nose 60 out of the path of the nipple 59 as soon as the lever 61 is liberated by a lock ing pin 65 which normally holds it in its operative position until the departure of the projectile.

The disc 56 normally engages by means of its circumference with a lateral notch 26 in the body of the striker 23 so as to retain vided-in the periphery ofthe disc 56 does not register withthe edge of the notch 26. As soon as the lever 61 is immobilized in its operative position by the pin 65 (that is to say during the whole time of its transport, its K This. setting is effected with the. aid of the key a by turning the same on the body of thefuse in clockwise direction with the aid of an appropriate timing device. By so doing, a pinion 67 is rotated which is rendered integral with this key by a diametrical tenon 17 on the'lower end of the latter. i This pinion 67 is freely mounted on a cylindrical lug 68 secured to the center of the upper transverse plate of the clockwork casing. Normally it meshes with a-sliding pinion 69 mounted on a square portion 70 of an auxiliary winding shaft 71. i

This shaft is journalled in openings provided in the transverse plates of the clockwork frame and is prevented from axial displacement in one direction by a pin 72 engaging the underside of the upper transverse plate and in the other direction by a plate 83 hereinafter described forming an abutment near its lower end. At its upper end the shaft 71 is prolongated by a reduced screw threaded extension 73 screwed on which is a nut 74 which forms a bearing surface for a spring, 75 tending to disengage the sliding pinion 69 from the pinion 67 when the pinion 69is liberated by the fork 76 of a lever 77 which is pivotally mountedv on a screw 78 secured in the upper plate of the clockwork mechanism;

This lever 77 is provided on one of lateral edges with a bent down finger 101 operating in a circular slot 79 which is cut in said upper plate and which has the. function to immobilize the regulating member to the moment of the departure of the projectile for the purpose hereinafter explained.

The lever 77 is held in its operative position (Fig. 2) to the moment of the departure of the projectile by a pin 81 operating by inertia like the pin 65. On being liberated by this pin 81 the lever 77 is rotated aboutthe screw 78 under the action of the centrifugal force, thus abandoning the sliding pinion 69 to the action of the spring 75.

When the key a is actuated with a view to elfectingthe setting as indicated above, the sliding pinion 69 which is held in mesh with the pinion 67 to the moment of the departure of the projectile by the lever 77 is actuated in counter-clockwise direction,

l al I whereby in the rotation of the shaft 71,

the shaft 39 is rotated in clockwise direction with the result on the one hand of winding the power spring 35, and on the other hand of driving, likewise in clockwise direction, the retaining disc 56 for the striker through the intermediary of reducing gears 43, 44 and 54, 55, whereby the setting of the fuse is realized.

When the clockwork is automatically started on the departure of the projectile in the manner hereinafter described, the power shaft 39 commences to rotate in counter-clockwise direction under the action of the force stored in the clockwork spring 35 and all of the rotary parts of the winding and setting mechanism are caused simultaneously to travel in the opposite direction, however, the same course which they have traversed during the winding up with the exception of the key 4 and of the pinion 67 which is then uncoupled from the sliding pinion 69.

The disc 56 is thus returned to the position which it occupied before the winding of the fuse, namely, the position in which it is fitted when leaving the workshop, but since at this moment the nose 60 on the lever 61 is no longer in the path of the pin 59, and on the other hand the force given out by the power spring, continues to act on the pinion 55, the disc continues to rotate in counter-clockwise direction until the edge of its notch 66 coincides with the edge of the notch 26 in the striker 23.

The latter is then abandoned to the action of the percussion spring 27.

In order to ensure that the power shaft 39 is driven by the clock spring 35 at a uniform speed in spite of the action of the centrifugal force on the turns of this spring provision is made of a regulating mechanism for braking the transmission of the motive force in a manner proportional to the acceleration exerted by the centrifugal force on the turns of the clock spring 35 and for neutralizing, on the-other hand, all the irregularities which might occur in the giving-out of the motive power.

This mechanism may be of any appropriate type and for this reason has not been represented in the drawing.

In order on the other hand to counteract losses of the motive force during winding while it is being stored in the power spring 35 and at the end of the winding to fix the setting position chosen, an improved locking device is provided enabling a much greater number of locking positions to be obtained than in any similar devices hitherto known.

This locking device is the object of the copending application Serial No. 39,699 filed June 26, 1925 and is described here only for facilitating the comprehension of the winding and setting device forming the object of the present invention.

This mechanism comprises a ratchet 83 in the shape of a disc keyed on the square end-of the motor shaft 39. This disc is provided with an upper circular edge cut with ratchet teeth 84 to the number of 2000. The ratchet 83 rests on the lower plate 83 of the clock frame work and supports a crown shaped pawl 85 likewise provided with ratchet teeth 86 of the same number but opposed to the teeth 84.

This pawl is held in engagement with the teeth of ratchet 83, that is to say, the teeth 84 and 86 are normally maintained in mesh by a flat spring 87 constituted by four bent lugs 87 bearing resiliently on the crown pawl 85.

From the workshop the spring parts 87 are delivered as part of a ring 87 screwed on the ratchet 83 as shown in Fig. 1. They are bent over the member 85 so as to exert pressure thereon parallel with the axis of the fuse.

During the simultaneous Winding and setting of the fuse, the ratchet 83 is free to turn with the motor shaft 39 in clockwise direction without driving the pawl 85 (then immobilized angularly by the regulating mechanism) because of the direction of the teeth 84 and 86, the inclined flanks of which glide one on the other thus enabling the pawl 85 to be axially displaced in opposition to the springs 87 by the height of the ratchet teeth.

At the moment of the departure of the projectile, however, the motor shaft 39 commences to rotate in counter-clockwise direction under the action of the clock spring 35, and the ratchet 83 then drives the pawl 85 (liberated by the regulating mechanism) in the same direction.

This pawl thus freed is then able by means of an internal toothed rim 88, to function as a member for transmitting the motive force to the regulating mechanism then liberated by the offset finger 101 on the lever 77.

The function of the fuse above described is as follows:

Assuming the use of a constructional form in which the clock spring is capable of receiving eight winding revolutions and in which the pawl 85 as well as the ratchet 83 is provided with a rim of 240 irreversible teeth.

Supposing also that this fuse is delivered from the Workshop set up for a minimum bursting duration of half a second with on the other hand an advance winding turn of its clock spring wound in reserve and with all its safety members i. e. the inertia nipples 65 and 81 and the centrifugal levers 61 setting positionsof the fuse with their proportionate corresponding winding turns will be determined by the product of the number of ratchet teeth 84:, in the above case 240, and the number of winding turns, that is to say, the number of revolutions performed.

by the power shaft 39 during the simultaneous setting and winding of the fuse, ,in the example chosen eight; It therefrom results that there are 240 8 19.20 different setting positions.

Supposing, as would in fact apply in the case of the construction described, that the unit of setting chosen is one-twentieth of a second, the maximum setting of the fuse will, therefore, give a duration of the function of the clockwork between the instant of the departure of the projectile and the moment of its, ignition equal to 1920, divided by 20, that is to say, 96v seconds. The f'use could,

thus be set to one-twentieth of asecond for an appropriate timing device in clockwisedirection. 7

Thus for example, if it were desired to obtain an interval before. ignition of 60 3/20 seconds, the key 4 would be rotated first through five complete turns onitselfand then through an angle of 4 30'.

In doing this, the driving shaft 39 would likewise perform five revolutions plus three locking movements in the clockwise direction through the agency of the gear wheels 67,69 and 82, 42. 7

During this rotation of the shaft39 clriv ing the ratchet 83 there will be 240 5+3 equal to 1203 successive lo'ckin'g movements (that is to say, small axial displacements) of the pawl member 85 which is immobilized in the angular sense, in the position which it occupied on its delivery from the factory by the locking lever 77 of the rotary setting member.

Through the two reduction gears 43, 44

and 5d, 55, this rotation of the power shaft' will be transmitted on the other'hand to the retaining disc 56 of the striker which will then describe in clockwise direction an angle equal to 96 since itperforms a complete revolution on itself during the mechanism maximum working period of the clockwork which is 96 seconds.

In. this way are effected simult'antously the winding and the proportionate setting of liberating the rotary setting member and.

the lever 61 for withdrawing its nose 60 from the path of the stop 59 o'f the retaining disc 56. I

After. thisthere is no further obstacle to the rotation of the power shaft 39 in counter clockwise direction under the action of the clock spring. 35. i p fWhile the rotation of theshaft takes place, all the rotary parts of the winding and setting mechanism of the fuse with theexcepti'on, however, of the key 4t and of the pinion 67 integral therewith, will travel in'th'e opposite direction through the same angle which they have, traversed during the firm ing ofthe. fuse plus a [certain angle determined by the travel yet to be traversed by the retaining disc 56 of-the striker commend ing fromthe initial position of setting to half a second for arriving in the position in which the striker is released-.3

The-motive force requisite for causing this disc to traverse this complementary path will .be provided for by the excess turn of winding applied to the clock spring 35 in the course of the manufacture of the fuse.

What I claim is g a 1. In a mechanism for. simultaneously winding and setting a mechanical fuse for artillery projectiles of the type described, drive shaftarranged in the axis of the fuse, an auxiliary shaft, a rotary setting member, reduction gears connecting the said auxiliary shaft and rotary setting member, and reduction gears connecting the said auxiliary shaft and drive shaft, the said gears being constantly in mesh in order to distribute the total duration of the movement of the fuse upon several turns of the drive shaft.

In a mechanism for simultaneously wind'ing'and. setting a mechanical fuse for artillery projectiles of the type described, a clockwork drive shaft arranged in the axis of the fuse, a winding shaft, gears connecting the winding shaftv and clockwork drive shaft, a rotary, setting member, and reduction gears constantly in. mesh with said member and drive shaft in orderfto distribute the total duration of the movementshaft.-

3. In a mechanism for simultaneously winding and setting a mechanical fuse for artillery projectiles of the type described, a clockwork drive shaft, a winding shaft, gears connecting the winding shaft with the clockwork drive shaft, a rotary setting member, reduction gears in constant mesh for connecting the said clockwork drive shaft and rotary setting member, a sliding pinion on the said winding shaft, a key normally geared to the sliding pinion, and de vices for normally maintaining the said sliding pinion in position to be turned by the said key.

4. In a mechanism for simultaneously winding and setting a mechanical fuse for artillery projectiles of the type described, a clockwork drive shaft, a winding shaft, gears connecting the winding shaft with the clockwork drive shaft, a rotary setting member, reduction gears in constant mesh for connecting the said clockwork drive shaft and rotary setting member, a sliding pinion on the said'winding shaft, a key, a gear on the said key normally meshing with the said sliding pinion, means for normally maintaining the sliding pinion in mesh with the gear on the key, and means operative upon the firing of the fuse for shifting the said means to release the said pinion and to free the same from the gear on the key thereby permitting the actuation of the said clockwork drive shaft.

5. In a mechanism for simultaneously winding and setting a mechanical fuse for artillery projectiles of the type described, a clockwork drive shaft, a winding shaft, gears connecting the winding shaft with the clockwork drive shaft, a rotary setting 'member, reduction gears in constant mesh for connecting the said clockwork drive shaft and rotary setting member, a sliding pinlon on the said winding shaft, a key, a gear on the said key normally meshing with the said sliding pinion, a pivoted lever having a hooked end adapted to lie normally under the said sliding pinion to maintain the same in mesh with the gear on the said key, and means operative upon the firing of the fuse for releasing and moving the hooked end of the said pivoted lever from beneath the sliding pinion.

6. In a mechanism for simultaneously winding and setting a mechanical fuse for artillery projectiles of the type described, a clockwork drive shaft arranged in the axis of the fuse, a winding shaft, gears connecting the winding shaft with the clockwork drive shaft, a rotary setting member, reduction gears in constant mesh for connecting the said clockwork drive shaft and rotary setting member, a sliding pinion on the said winding shaft, a key, a gear on the said key normally meshing with the said sliding pinion, a pivoted lever having a hooked end adapted to lie normally under the said sliding pinion to maintain the same in mesh with the gear on the said key, means operated by the said pivoted lever and operative when the lever is in its initial position for maintaining the clockwork mechanism inoperative, and a pin for normally maintaining the said pivoted lever in position with the hooked end thereof beneath the said sliding pinion and which pin is automatically withdrawn upon the firing of the fuse to release the pivoted lever and the means carried thereby for maintaining the clockwork inoperative, thereby permitting the clockwork drive shaft to actuate the same. i

In testimony whereof I afiix my signature.

ANDRE VARAUD. 

